Sterling silver whitby jet wide marquise celtic necklace p1393 this elegant necklace features hand carved blue john that has been sourced directly from the derbyshire blue john cavern in castleton the highly polished blue john marquise gemstone is framed within a unique sterling silver celtic design with the pendant being presented on a 18 sterling silver chain all our blue john jewellery is designed and crafted within our very own workshops in ashbourne derbyshire where a team of skilled